lentymarkets / plentyOne API Expert Needed

We are looking for an experienced plentymarkets / plentyOne professional to help us clarify a technical and commercial integration question. Background We currently use the plentyOne REST API to: Fetch orders from plentyOne Push back shipment / tracking information This part is already working. One of our clients now requires that the actual shipping label document also be pushed back into plentyOne. We have investigated the REST API, but it appears that uploading or attaching the actual label through the REST API may not be supported, or at least not in the way we need. What We Need We are looking for someone who has strong experience with plentymarkets / plentyOne integrations and ideally plugin development. We need help answering the following questions: Is it possible to upload or attach the actual shipping label to an order using the existing plentyOne REST API? If this is not possible via REST, would this require a custom plentymarkets / plentyOne plugin? Can such a plugin remain private and be used only for our client integration? Would developing and using a private plugin require a commercial agreement with plentymarkets? Are there any technical or marketplace restrictions if the plugin is not published in the plentymarkets Add-ons Store? Deliverable We do not need full plugin development yet. The first deliverable is a short technical consultation / written assessment explaining: Whether the label upload requirement is technically possible The recommended implementation approach Whether a plugin is required Any known commercial or licensing implications for private plugin usage Suggested next steps if development is needed Ideal Candidate You should have experience with: plentymarkets / plentyOne REST API plentyOne plugin development Order, shipping, fulfillment, and document handling in plentyOne Add-ons Store / private plugin deployment rules plentymarkets commercial or partner requirements, if applicable Please include examples of previous plentymarkets / plentyOne API or plugin work in your application. We would like to start with a short paid consultation and may extend the project if plugin development is required.